Science In Real Life

A tornado is one of the most striking reminders that the backdrop of life on the surface of the planet Earth is a collection of extremely powerful forces every bit as dynamic as the complex network of small creatures that scurry about attempting to find things like food and happiness. Most of the time these larger forces keep to themselves and don’t cause any trouble, but when they collide they cause mayhem and chaos on a scale your average comic book villain can only dream of. In the case of a tornado, it’s a collision between massive bodies of moving air in just such a way as to produce gaseous drills of death near the surface.

One of the most important and useful concepts in physics and engineering is equilibrium. A system not in equilibrium will continue to evolve until its various parts are exerting only equal and opposite forces on each other. Tilt a see-saw, and let it go. In the instant you release, the upper end is pulling on the lower end harder than the lower end can pull back; thus does the see-saw return to its original position. Objects not fully supported fall until they are, springs de-compress until they reach their normal extent, and eventually the Democrats win an election.

What does this have to do with tornadoes? Suppose I have a nice warm Kansas, fresh out of the July oven. Lots and lots of hot air coming up from the surface. Up above is a giant mass of cold air – this is a system out of equilibrium. The hot and cold air mix in a very messy fashion, causing clouds to form, which then gives rise to a huge thunderstorm as the mixing continues. But wait, there’s more! Turns out, this is no ordinary thunderstorm: it has wind shear, the very latest in fashionable accessories for today’s meteorological phenomenon on the go. Wind is traveling in one direction near the ground, and in the opposite direction high above.

Now we’re on a roll, literally. The opposing wind fronts cause the air to spin like a wheel rolling along the road. The updraft of warm air tilts the rotation upward, and suddenly we have a vertically spinning column of air. Warm air from near the ground enters the cloud, and rises in an upward spiral called a mesocyclone. When it gets to the top, it displaces colder air, pushing it down on almost all sides of the mesocyclone (leaving a gap for new warm air to come in). Here’s the kicker: the descending cold air pulls the cyclone down towards the ground and compresses the tip. That makes it spin faster (Advanced note: conservation of angular momentum). It picks up dust and water droplets, becoming visible, and by this point it’s going so fast that it starts picking up damn near everything else. Congratulations, it’s a bouncing baby tornado. It’ll keep going as long as there’s a fresh supply of warm air entering at the bottom.

To summarize: A tornado occurs when warm air and cold air mix in such a way that the warm air spins its way upwards, and the surrounding cold air forces a very tight, rapid spin. If you’re still wondering where the initial spin comes from, imagine two ice skaters facing each other across the ice. They start skating toward each other, almost head on – if they kept going straight they’d brush past each other. But at the last second, they reach out and link arms. Suddenly they’re spinning around, the crowd goes wild, and the Winter Olympics have begun.

The reason tornadoes occur so frequently in the midwestern region surrounding Kansas is a geographic accident. What you have there is a nice flat plain between a northern source of cold air and a tropical source of warm air. It’s a perfect laboratory for sliding warm and cold air past each other. The eddies that form are a natural consequence of the mixing. The fact that the eddies often attain wind speeds upwards of 150 miles per hour is a reminder that the air we think nothing of breathing can pack a serious wallop once it really gets moving.

What I’ve explained here is only part of the story – what are called supercellular tornadoes. They are the most common, but there are other mechanisms that cause similar phenomena. Atmospheric fluid dynamics is an exceedingly complicated subject, and research is ongoing. Finally, I found these two animations instructive. Take a look if you’re having trouble visualizing how the air moves:

http://esminfo.prenhall.com/science/geoanimations/animations/Tornadoes.html

http://access.ncsa.uiuc.edu/Stories/supertwister/page3.htm

It may seem incongruous at first for one of these essays to be about all of science, but I feel it worthwhile to clarify the true nature of this venerable institution. Today you all get to peek into the methods behind the biggest thing to hit civilization since that carpenter from Nazareth. Words like ‘scientific’, ‘scientist’, and ‘science’ are thrown around quite a bit what with the technological tendencies of our culture, and sometimes they are used incorrectly, or at least without regard to the subtleties behind the lab coats.

For starters, a lab coat does not a scientist make. If you ask a hundred people what they first think of when they hear the word “scientist”, lab coats, petri dishes, and bubbling beakers will comprise the majority of the answers (crazy hair and death rays optional). Fact is, many people who wear lab coats are not scientists, and many scientists don’t wear lab coats. A scientist is anyone conducting an investigation to determine the rules that govern the Universe according to the principle of reproducible results.

That one principle is at the heart of the scientific perspective. Most of us in grade school were taught “the scientific method”, a list of up to ten separate steps handed down from on high like a certain other list of ten things I won’t mention. Now, following those lists is a perfectly valid way of conducting science, but taken alone they present a distorted and incomplete picture of how science actually happens. For example, often a scientist will not have a specific hypothesis in mind when conducting an experiment, but will instead draw conclusions directly from patterns observed in the data. The lists also do not tell us why this method is scientific – the answer is the principle of reproducible results.

It goes all the way back to the goal of science: to discover the rules that govern the Universe. A rule, by definition, is never broken, no matter how hard mischievous little children try. Suppose I observe something, and I decide that I saw factor A and factor B combine to make factor X. Before I go declaring the new rule that A plus B makes X, I have to check that this is always the case. So I go back home, break out the alphabet soup, and combine A and B again. If they don’t make X, then “A plus B makes X” is not a rule. Maybe factor C was also present and I missed it, or maybe they make factor Y and I thought it was X, or maybe it was something else entirely. That is science, and this is why philosopher Karl Popper credited falsifiability as the defining principle of scientific investigation – it is the testing of claims that could be proven wrong.

Now, here’s the kicker. Suppose I get home and find that once again, A plus B makes X. I still can’t say that A plus B always makes X, because that would require an infinite and continuous array of tests, running all the time forever, and who has that kind of time? Instead, what I do is put the word out to all my fellow scientists all over the world that it looks like A and B make X. They all run the test themselves, under a variety of conditions. If even one of them reports back that A and B don’t make X, then the potential rule “A plus B makes X” is invalidated, and needs to be amended to account for whatever additional condition(s) need to be present to make X.

The basic structure I’ve constructed here is called inductive reasoning. The sun has risen in the east every day of recorded human history – it hasn’t missed a day in 10,000 years (and you thought you had a good attendance record). So inductively we conclude that the sun will almost certainly rise in the east tomorrow. But that “almost” is crucial. There is a chance, however small, that the sun will rise in the west tomorrow, or not rise at all, or suddenly be a bowl of spaghetti. All the conclusions that science has drawn about the Universe could be invalidated next Tuesday if the experiments give us different results. All the “laws” of science are only valid in an up-to-now sense.

Which brings me to my final and most important point. Science is a process, not a body of knowledge. Science is a means of obtaining information, not the information itself. Science is a way of thinking, not a thing to believe. Unfortunately for those of us in a global 21st century civilization, science had a head start that would make Doogie Howser jealous. The body of knowledge it has produced is massive, so the majority of our experience with science growing up is “Here, learn everything in this book.” As a result, the misconception spreads that Science is an impenetrable monolithic entity accessible only to geniuses of superhuman intellect. This is patently false – as a scientist I can tell you that science is neither impenetrable nor monolithic.

But seriously, anyone can do science. Yes, even you. In fact, you already have. Probably today. Any time you look at something twice to make sure you saw what you thought you saw, or check whether something you heard is actually true, or taste-test that mysterious leftover in the fridge to see if it’s still good, you are using a scientific methodology to acquire information about your environment. Cool, huh?

I leave you with a rule of thumb to guide you on what is and isn’t science: any subject that has the word “science” in its name isn’t one.